Cold neutral hydrogen gas in galaxies

Dutta, Rajeshwari

doi:10.1007/s12036-019-9610-5

Cited by 7 publications

(1 citation statement)

References 166 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In and around galaxies, the neutral gas phase plays an important role as an intermediate medium between the ionized gas accreted from the Intergalactic Medium (IGM) and the molecular gas [26]. Therefore, it serves as a reservoir for molecular and star-forming gas, playing a crucial role in the formation and evolution of galaxies.…”

Section: Hi 21cm Linementioning

confidence: 99%

Radio astronomy with the compact radio telescope (CRT) and radio interferometry simulation

Yang

View full text Add to dashboard Cite

Section: Hi 21cm Linementioning

confidence: 99%

Radio astronomy with the compact radio telescope (CRT) and radio interferometry simulation

Yang

View full text Add to dashboard Cite

Probing galaxy evolution through Hi 21-cm emission and absorption: current status and prospects with square kilometre array

et al. 2022

Self Cite

View full text Add to dashboard Cite

One of the major science goals of square kilometre array (SKA) is to understand the role played by atomic hydrogen (Hi) gas in the evolution of galaxies throughout cosmic time. The hyperfine transition line of the hydrogen atom at 21-cm is one of the best tools to detect and study the properties of Hi gas associated with galaxies. In this paper, we review our current understanding of Hi gas and its relationship with galaxies through observations of the 21-cm line both in emission and absorption. In addition, we provide an overview of the Hi science that will be possible with SKA and its precursors and pathfinders, i.e., Hi 21-cm emission and absorption studies of galaxies from nearby to high redshifts that will trace various processes governing galaxy evolution.

show abstract

HALOGAS: Strong constraints on the neutral gas reservoir and accretion rate in nearby spiral galaxies

Kamphuis

Jütte

Heald

et al. 2022

A&A

View full text Add to dashboard Cite

Context. Galaxies in the local Universe are thought to require ongoing replenishment of their gas reservoir in order to maintain the observed star formation rates. Cosmological simulations predict that such accretion can occur in both a dynamically hot and cold mode, depending on the redshift, halo mass and the details of the included feedback processes. However, until now observational evidence of the accretion required to match the observed star formation histories is lacking. Aims. Within the framework of the Hydrogen Accretion in LOcal GalaxieS (HALOGAS) survey, this paper attempts to determine whether galaxies in the local Universe possess a significant reservoir of cold neutral gas and what would be the accretion rates derived from such reservoirs. Additionally, with this moderately sized sample we can start to investigate whether the observed accretion is connected to intrinsic properties of the galaxies like Hubble type, star formation rate or environment. Methods. We search the vicinity of 22 nearby galaxies for isolated H i clouds or distinct streams, that are not yet connected to the galaxy's disk, in a systematic and automated manner. The HALOGAS observations were carried out with the Westerbork Synthesis Radio Telescope and represent one of the most sensitive and detailed H i surveys to date. These observations typically reach column density sensitivities of ∼ 10 19 cm −2 over a 20 km s −1 width. Results. We find 14 secure H i cloud candidates without an observed optical counterpart in the entire HALOGAS sample. These cloud candidates appear to be analogues to the most massive clouds detected in the extensive cloud distributions around the Milky Way and M 31. However, on average their numbers seem significantly reduced compared to these galaxies. Within the framework of cold accretion, we constrain upper limits for H i accretion in the local Universe. The average H i mass currently observed in a state suggestive of accretion onto the galaxies amounts to a rate of 0.05 M yr −1 with a stringent upper limit of 0.22 M yr −1 , confirming previous estimates. This is much lower than the average star formation rate in this sample. Our best estimate, based on the Green Bank Telescope detection limits of several galaxies in the sample, suggests that at most another 0.04 M yr −1 of neutral hydrogen could be accreted from clouds and streams that remain undetected. Conclusions. These results show that in nearby galaxies neutral hydrogen is not being accreted at the same rate as stars are currently being formed. Our study can not exclude that other forms of gas accretion, such as those provided by direct infall of ionized intergalactic gas or the condensation of coronal gas, triggered by galactic fountain activities, are at work. However, these observations also do not reveal extended neutral gas reservoirs around most nearby spiral galaxies.

show abstract

Cold neutral hydrogen gas in galaxies

Cited by 7 publications

References 166 publications

Radio astronomy with the compact radio telescope (CRT) and radio interferometry simulation

Radio astronomy with the compact radio telescope (CRT) and radio interferometry simulation

Probing galaxy evolution through Hi 21-cm emission and absorption: current status and prospects with square kilometre array

HALOGAS: Strong constraints on the neutral gas reservoir and accretion rate in nearby spiral galaxies

Contact Info

Product

Resources

About